2003 REU Students' AAS Abstracts

We present initial results
from an Ha and
X-ray emission survey
of
the young cluster NGC 2264 in the
Mon OB1 association. Approximately
450
emission Ha stars
were identified in a 25' ×
40' field roughly centered between
the
O7V multiple
star S
Mon and the Cone Nebula. The Ha emission survey was carried
out
using the wide-field grism spectrograph
on
the University of Hawaii 2.2 meter
telescope and the Gemini Multi-Object
Spectrograph (GMOS).
The XMM-EPIC
observations of the cluster are
discussed in detail in
the accompanying
poster by David et al. (2004).
Additionally, we obtained optical
(BVRCIC) and near infrared (JHK)
photometry for selected
fields in
NGC 2264 to supplement published
data
from previous investigations and
to ensure coverage for the majority
of
detected emission Ha stars
and X-ray sources. Optical color-magnitude
diagrams are presented
and used
to derive ages and masses from theoretical
isochrones and evolutionary
tracks
for the candidate pre-main sequence
stars. We analyze the
X-ray luminosity
functions of classical and
weak-line T Tauri stars in NGC 2264
and seek correlations among LHa,
LX, spectral type and
theoretical
age. Finally, the distribution and
density of emission Ha stars
in the cluster are discussed and
compared with those found
in other
star forming regions including IC
348,
IC 5146 and NGC 2362.
This research was supported in part
by the NASA XMM-Newton Guest Observer
program and the NASA
Graduate Student
Research Program.

X-ray images of the
heavily-populated, young,
star-forming region NGC
2264
were obtained with the XMM-Newton
European Photon Imaging Cameras
(EPIC).
The region was observed in two
30' fields of view; the southern
field
contains the Cone Nebula, while
the northern field is centered
near the
bright O star, SMon. In all, 320
X-ray sources were detected above
a 3
s detection
level of Lx =
3 × 1029 ergs s-1
. The large majority
of
the
sources have optical counterparts
from earlier surveys of the pre-main
sequence population of
the cluster.
A dozen sources have no identified
optical counterpart and
therefore
are possible candidates for very
young,
deeply embedded protostars. We
describe our procedures for extracting
source count rates and
pulse-height
spectra, light curves, and X-ray
luminosities. More detailed
analysis
of these results and a comparison
with ground-based optical
and
infrared data appears in the accompanying
poster by Dahm et al.
(2004).
This research was supported in
part by the NASA XMM Guest Observer
program
and by the NSF Research Experience
for Undergraduate Program.

Previous research has
hinted that magnetic fields
play a key role
in the
formation of cores in star forming
molecular clouds. However, the
extent
of that role is not fully understood.
Here, we compare polarization
data
of observed cores with clumps
formed in a simulated model
of turbulent
molecular clouds. Through an
investigation of the polarized
angle
dispersion of both sets of data,
it was found that the simulations
were
accurate in representing cores
formed with either a low turbulence
or
within a relatively strong magnetic
field. Also, through investigation
of
data's polarized flux, the observed
sources are found to have formed
in
fields that are more ordered
than those modeled in
the simulations.
This
finding is also supported by
the calculated magnetic
field strengths
of
the observed cores via the Chandrasekhar-Fermi
method. This research will
aid in understanding the conditions
of star formation within turbulent
molecular clouds.
This work was funded by the
National Science Foundation's
Research
Experience for Undergraduates
program.

Since Richard Carrington's
1859 discovery of White
Light Flares
(WLFs),
only fifty other WLFs have
been observed. While the predicted
frequency
was 15.5 (± 4.5) per year for
solar cycle 20, the lack of sensitive
instruments makes WLFs extremely
rare. Past observations suggest
that WLFs
do not accompany all high-energy
events, and that some specific
initial
conditions and mechanisms
produce WLFs.
To analyze this claim, we
found a WLF by combing through
a list
of X
class
events. This X5.6 flare occurred
at AR 9415 on April 6th, 2001
(UT 19:14)
and was accompanied by a halo
CME. After confirming this
event to be
a WLF
using Imaging Vector Magnetograph
data, we found microwave,
EUV, optical,
soft X-ray, and magnetogram
data. Our data suggests that
this WLF
erupted
through the same mechanisms
as the standard flare models,
but
was more
energetic.
This work was funded by the
National Science Foundation's
Research
Experience for Undergraduates
program.

The research project
my mentor, Dr. Jim Heasley,
and I worked
on this
summer involved a search
for extra-solar planets.
My research
was
supported by the National
Science Foundation. The
search was conducted
using a drift scanning
method with two 0.1-meter
diameter
telescopes. By
using these small telescopes,
we were capable of attaining
over 2
million
stars per night and over
30 million stars
for data analysis. The
telescopes are mounted
on
Haleakala, Maui at an
altitude of 10,000
feet.
Our main interest was
to detect subtle decreases
in the intensity
of the
measured stars. Sixteen
nights of observations
were used
for our data
analysis which covered
a range in right ascension
from 40
degrees to 200
degrees. For this particular
data set, a Stellar Photometry
Software
package, written by Janes & Heasley
(1993), produced information
for each star such as
the raw instrumental
magnitudes, ID numbers,
(x,y) coordinates, and
an estimated
error for each reported
magnitude. In order to
flag down these
transits and detect time
history of any
measured object, it was
in our best interest to
establish
a
database. The
database is useful to
us in such a way that
large numbers
of stars
can
be
stored and examined, we
are allowed flexibility
in examining
the data
in a
number of ways, and incorporating
additional observations
as they become
available will be much
more simplified. The observing
program on Haleakala
is set to operate for
a three
year period.
This work was funded by
the National Science Foundation's
Research
Experience for Undergraduates
program.